In radio communication systems, information, e.g. voice, picture information or data is transmitted with the aid of electromagnetic waves via a radio interface between a base station and a subscriber station, e.g. a mobile station. The radiation of the electromagnetic waves in this case is by carrier frequencies that lie within a frequency band provided for the particular system. For future mobile radio systems, the radio interface will be subdivided, according to the TD/CDMA access method or FD/CDMA access method, into transmission channels that separate the radio resources of the radio interface for the individual subscriber stations. For UMTS (Universal Mobile Telecommunication Systems) or other third-generation systems, frequencies, for example in the approximately 2000 MHz frequency band, are provided for the transmission channels.
In the UMTS system, a connection is established between a base station, also designated as node B, and a subscriber station. The base station is assigned a controlling radio network controller that manages the radio resources of the base station and through which a connection to a core network is established. Professionally, the controlling radio controller is frequently known as a controlling radio network controller or CRNC. The subscriber station is assigned a serving radio network controller in the UMTS system, often known as a serving radio network controller or SRNC. This serving radio network controller is usually the radio network controller through which the connection to the subscriber station was initially established and it remains assigned to the subscriber station even if the subscriber station moves to the area of a different radio network controller. The serving radio network controller is responsible for the configuration of the subscriber station. To do this, the subscriber station transmits dedicated measuring protocols to the serving radio network controller for the duration of the connection. These measuring protocols are transmitted transparently for the controlling radio network and the base station.
In the UMTS and other third-generation systems, a common channel is provided, known as a shared channel, to which several subscribers can be assigned at the same time for data transmission between a base station and a subscriber station. The requirements of the individual subscribers in this case are managed in a queue in the base station. The assignment of resources for the common channel, however, takes place in the controlling radio network controller that is assigned to the base station.
In many mobile radio systems, particularly those of the third-generation of mobile radios, various services are offered for data transmission, to which different service quality parameters, also known as quality of services, are assigned. These can for example be agreed transmission rates or agreed delay times. Services to which the same quality of services parameters are assigned are allocated to a quality of service class.
If the common channel becomes overloaded, the quality of service parameters for the individual services can therefore no longer be maintained. It has therefore been proposed that the base station informs the controlling radio network controller when it is determined that individual quality of service classes can no longer achieve the required and agreed quality of service parameters. This notification takes place in something called a common measurement. In this case, the controlling radio network controller of the base station allocates additional resources for the common channel. This does not take account of how the radio conditions for individual subscriber stations appear. Situations are conceivable whereby the quality of service requirements can only be inadequately fulfilled by resource allocation because the radio conditions for individual subscriber stations are very bad.